Medical experts warn the COVID-19 variant codenamed "B.1.427/B.1.429" now dominant in California is showing signs of greater infectiousness, severe illnesses and a higher probability of death.
Also of concern is the variant's apparent ability to neutralize antibodies generated by COVID-19 vaccines, or those created from prior infection to SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the virus that causes COVID-19.
First detected in September 2020, the California strain has spread far too fast. It now accounts for more than 50% of all coronavirus samples in California subjected to genetic analysis. Compared to mutations more prominent in California last autumn, B.1.427/B.1.429 is confirmed to have enhanced transmissibility.
Samples collected from counties suggest B.1.427/B.1.429 is 19% to 24% more transmissible. The strain's infectiousness, however, was much greater in some instances.
In one nursing home outbreak, the new strain spread at a rate that was six times higher than earlier mutations. State health experts pointed to a correlation between higher infections rates and evidence of the new mutation's presence.
Laboratory results also confirmed the enhanced transmissibility of B.1.427/B.1.429, which is also known as "20C/L452R." People infected with the mutation had viral loads in the nasopharynx that were twice as high compared to people infected with other SARS-CoV-2 strains.
This outcome, which was revealed by an analysis of viral samples from around the state, makes it quite likely each individual infected by B.1.427/B.1.429 will go on to infect more people than previous mutations.
Scientists at the University of California, San Francisco (UCSF) said the cluster of mutations characterizing the California strain should mark it as a "variant of concern" similar in dangerousness to mutations from the United Kingdom, South Africa and Brazil.
The team of geneticists, epidemiologists, statisticians and other scientists led by Dr. Charles Chiu, Director, UCSF-Abbott Viral Diagnostics and Discovery Center, conducted a wide-ranging analysis of B.1.427/B.1.429 in the state. The results were disheartening.
"The devil is already here," said Chiu. "I wish it were different. But the science is the science."
Lab results showed the California strain more damaging to human body organs. A coronavirus engineered by scientists to have only the B.1.427/B.1.429 mutation was able to infect human lung tissue at least 40% more readily compared to circulating variants without the mutation.
Alarmingly, the California strain revealed itself more resistant to neutralizing antibodies generated in response to COVID-19 vaccines, as well as by a previous coronavirus infection.
Researchers said the reduction in protection was "moderate ... but significant" compared to existing variants.
"I do anticipate over time it is going to have an effect on vaccination," said Chiu.
Though the magnitude of the neutralization varied from sample to sample, "it still is concerning," he said.
